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Learn C#: String, The Exception

C# String Comparison

In C#, string is a reference type, but it is compared by value when using ==.

// In this example, even if s and t are not referentially equal, they are equal by value:
string s = "hello";
string t = "hello";


// b is true
bool b = (s == t);

C# String Types Immutable

In C#, string types are immutable, which means they cannot be changed after they are created.

// Two examples demonstrating how immutablility determines string behavior. In both examples, changing one string variable will not affect other variables that originally shared that value.


//EXAMPLE 1
string a = "Hello?";
string b = a;
b = "HELLLLLLLO!!!!";


Console.WriteLine(b);
// Prints "HELLLLLLLO!!!!"


Console.WriteLine(a);
// Prints "Hello?"




//EXAMPLE 2
string s1 = "Hello ";
string s2 = s1;
s1 += "World";


System.Console.WriteLine(s2);
// Prints "Hello "

C# Empty String

In C#, a string reference can refer to an empty string with "" and String.Empty.

This is separate from null and unassigned references, which are also possible for string types.

// Empty string:
string s1 = "";


// Also empty string:
string s2 = String.Empty;


// This prints true:
Console.WriteLine(s1 == s2);


// Unassigned:
string s3;


// Null:
string s4 = null;
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